1. Field of the Invention
The present invention relates to a printed circuit board, and in particular, the printed circuit board having a connector housing mounted on the printed circuit board, positive and negative terminals, and lead wires of the terminals extending from the printed circuit board to the connector.
2. Description of the Related Art
In recent years, a hybrid vehicle (HEV) having an electric motor as a driving force, a fuel cell electric vehicle (FCEV), an electric vehicle (EV) have been spread. Each of these electric vehicles includes two types of batteries: a low voltage battery about 12 volts for starting an engine, and a high voltage battery for driving the electric motor.
A conventional printed circuit board mounted on such an EV is shown in FIG. 8. As shown in FIG. 8, the printed circuit board includes a substrate 10, a connector housing 11 mounted on the substrate 10, and terminal fittings 12 received in terminal insertion holes formed on the connector housing 11. The terminal fittings 12 include a high voltage positive terminal T+ and a high voltage negative terminal T− connected to positive and negative terminals of the high voltage battery. The terminal fittings 12 also include low voltage terminals T1 to T5 connected to the low voltage battery.
One ends of lead wires of the high voltage terminals T+, T− are projected from the terminal insertion holes formed on an upper row of a sidewall of the connector housing 11. The other ends of the lead wires of the high voltage terminals T+, T− are connected to terminals mounted on the substrate 10. One ends of lead wires of the low voltage terminals T1 to T5 are projected from the terminal insertion holes formed on a lower row of the sidewall of the connector housing 11. The other ends of the lead wires of the low voltage terminals T1 to T5 are connected to terminals mounted on the substrate 10. In the connector housing 11, the low voltage terminals T1 to T5 are interposed between the high voltage terminals T+, T−.
Further, a pair of slits 13 is formed between the terminals T+ and T1, and between the terminals T− and T5. These slits 13 are formed for securing isolation between the high voltage terminals T+, T− and the low voltage terminals T1 to T5 by elongating a distance along the substrate 10 therebetween.
Sometimes a conductive foreign particle 14 such as a piece of coil is mixed on the printed circuit board. Consequently, there is a problem when the conductive foreign particle 14 is touched to both the high voltage terminals T+ and T−, the high voltage battery is short-circuited.
Further, when there is a problem when the conductive foreign particle 14 is touched to any one of the high voltage terminals T+, T−, and some of low voltage terminals T1 to T5, the isolation between the high voltage terminals T+, T− and the low voltage terminals T1 to T5 is broken.
Therefore, the lead wires of the high voltage terminals T+, T− may be coated with insulating material. However, secure isolation is difficult due to uneven coating. Further, it takes cost to coat the lead wires. Further, because typical insulating material includes volatile material and environmental load, using the insulating material is not preferable considering an effect on the environment.
Accordingly, an object of the present invention is to provide a low cost printed circuit board able to prevent a mixed conductive foreign particle from short-circuiting positive and negative terminals.